Mil instructors would typically be a Flt Lt (or equiv) on second tour so basic would be over 45k GBP plus at least about 9k Flying pay. That's on the regular pay scales. The mil web of what you can be paid as spec aircrew is complex, but you should think in general well over 50k GBP.
https://www.raf.mod.uk/community/mur...6-17-FINAL.pdf